text:
Why are Low Cost Carriers ordering several hundred aircraft?
Indigo is a low cost carrier, which already has 99 A-320s in its fleet has  ordered 431 more. This airline currently covers 35 routes, while the full service carrier Emirates has 221 planes, and covers a fancy 164 routes. In its home country as well, the biggest player Air India has 102 planes and covers 95 routes. So, what are these LCCs planning to do with so many aircraft? Renting could be an idea, but you just do not go for renting as much as 4 times of your crew size.
Similarly,

AirAsia has ordered 304 A320s,
EasyJet has ordered 100 A320s,
RyanAir has ordered 100 B-737.
Norwegian has ordered 100 A320s, 100 B737,

In a sense, the answer is:  India has a BILLION people.  If you've been to say HK or Shanghai 15, 20 years ago .. visit Mumbai now.

Volume Orders Discounts
These result in significant discounts to the airline. While discounts are commonplace in the industry, Ryanair ordered 737-800 for an estimated 40-50 million dollars as compared to the list price of around 90 million dollars. With an order of that size Boeing could not risk losing it to another manufacturer, and will be satisfied with less profit per aircraft. Source
Fleet strategy:
Some airlines sell their old aircraft after only a few years while their value is still high but the maintenance costs start to increase. Increased maintenance is bad when you try to squeeze out as many flights as possible and you have small profit margins on every flight. You can find some of Ryanair's old aircraft by the company code (AS) with other operators by searching 737-8AS.
Another suggestion is that the customers perception of Low-Cost airlines is generally negatively biased and having new aircraft counters this effectively.
Old Aircraft
Some operators (such as charter operators) will not have the same sensitivity to a slightly higher fuel consumption on their aircraft. They may not use their aircraft the same number of hours, so having an increasingly expensive jet sitting on the ground is not cost-efficient. The aircraft ordered by IndiGo are all new fuel efficient A320NEO.

Some of these ideas are emphasized in your link.

Of its 530 orders from IndiGo, Airbus has so far delivered 99 aircraft. The airline currently has a fleet of 83 planes and has phased out 16 planes that were over six year old or among the first in its fleet.

A bit of Ryanair strategy is outlined in this document.

The aircraft ordered by Indiegogo they kickstarted an airline? :P

@Federico not in this case ;) but see this

It might be that Times of India are over-reporting the actual orders. The aircraft industry has various types of orders and options.
Other sources (pdxlight) say that Indigo has firm orders for 180 A320neos.
If Indigo replaced their existing A320s this would represent a doubling of their fleet size - still surprising but less so than the five-fold increase from 99 to 530 suggested.
Indigo have also signed a memorandum of understanding for 250 aircraft. This isn't a firm order. Indigo claim " The additional aircraft will enable us to continue to bring our low fares and courteous, hassle free service to more customers and markets and will create more job opportunities and growth." - presumably if their ambitious expansion plans do not work out as expected, this MoU will not be converted into firm orders.
There have been reports of an IPO for Indigo and other sources of funding.

The aircraft industry has various types of orders and options. - yes, that. When the Dreamliner finally came to production, many airlines ordered some only to later sell the bid for buy at a premium (to those who wanted the plane but found themselves too far down on the list).

Outfitting an airline with a single, modern type will yield the lowest operating cost once financing of the acquisition is secured and crew compensation stays low. This, together with the rebates connected to a big order, enables the airline to win any price war with its local competition, because its aircraft will consume less fuel and will be profitable at lower seat-mile prices than those of a competitor which operates a mixed fleet of different types and older aircraft.
Now the investor needs only some patience, and after a few years of losses he will be able to reap monopoly profits. This, at least, is the strategy behind such big orders of a single type.
By ordering large volumes, the airline can secure the highest possible rebates (up to 50%). This strategy is very similar to that of car rental firms which also buy cars in large volumes and with substantial rebates in order to sell them after some months (years in case of airlines) for more than they paid for them.

In addition to these wonderful points about getting a lower price for a mass-order, there are lots of unforeseen upsides to having a fleet of only a SINGLE type of (modern) airplane:

New planes live very long
New planes are more fuel-efficient than older ones
If there is only 1 type of plane it is very straightforward swapping out a plane if one requires repair
Aircrews only need to be trained & Certified for a single type of plane
Ground Crews
Pilots only need to be trained & certified for a single type of plane - This is a Big One. Afaik if an airline also has e.g. a Very Large Plane, the pilots need to be especially trained for that one, which does less routes than the smaller ones, which makes it a less cost-effective endeavour

Source:

I find the screen shot for that video quite amusing. Two aircraft with gear down pictured high above the clouds. The EasyJet even has flaps and thrust reversers deployed - I guess they're about to make an emergency descent!! My Photoshopometer is pegged! :)


text:
How similar/different are the roles performed by Military and Civil pilots?
Broadly, Military and Civil are the only two categories in which the Pilots can be classified on the basis of the roles performed by them. What are the similarities and differences in tasks performed by them?

I would argue your categories would be Military and Civilian. As I understand it, on the Civilian side there would be Commercial and Private or General Aviation. I am, however, far from the expert on these differentiations.

As mentioned Commercial should really be "Civilian" which includes Private and Commercial. Lets assume that military includes the various branches that employ pilots (Navy, Air Force, Marines etc).
In the end of the day everyone flies a plane...
A chunk of military aviation is devoted to combat related missions, this is something a civilian will never see (at least as far as I know). This includes but is not limited to surveillance, escorts, combat and other military related missions.
The military operates troop transport and cargo planes much like commercial operations do and they have pilots who fly them. I would think the tasks are very similar since moving people and cargo is moving people and cargo whether for the military or a civilian organization.
The military obviously had access to flying some planes that would be tough to get into as a civilian (fighter jets mainly). One operation that Civilian pilots will never see is take off and landing on a carrier. That is unique to Navy operations and as far as I know there is no way to do it as a civilian or even train for it (unless you can buy a carrier).
As far as regulations go the military aircraft and pilots are subject to military regulations (in terms of up keep and things like that) and must adhere to those rules which I believe are different in some cases than the FARs that govern US commercial and Private operations. That being said, if flying in US airspace the same rules apply to military planes that apply to civilian planes.

Late, I know.  I flew into DaNang on a leased civilian airliner, and out on a C-141.  Upon discharge I and my family flew from The Dominican Republic to Miami with a stop in Haiti.  It seems somebody named Papa Doc was interested in a small change in Haiti.  The result was deplaning and boarding  happened with the opposite side engine still running and little ol' me watching a firefight outside my window.  Civilian and military pilots sometimes cross pollinate.

The biggest difference is that most everything in commercial aviation is considered administrative in the military.  The tactical employment of our aircraft, the non-administrative portions of flight, is what separates military sorties from commercial flights.  This emphasis on tactical flying has also led to significantly different cultures between commercial and military aviation.  There isn't a commercial pilot I would stand a chance against in a game of FAR/AIM trivia, but I also doubt they'd fare much better if the tables were turned and the questions were related to carrier operations.  We are two separate organizations with two unique mindsets to flying.

Within commercial civilian flying the mission objective is to land safely at a destination. In operational flying in a 'deployment zone' the mission is to do many other things before you land somewhere safely. There are so many more factors to consider than just flying from A to B.
Areas of recent combat, rising threats, low-level flight, areas where fighting is imminent, mountain flying, attempting to minimise the impact on local population when you fly over their houses/vilages/cities, proximity to other air-assets that fly in the same mission. Just to name a few.
Even seemingly 'airline' types of transport in the military do have to consider many more factors during take-off and landing in a war-zone. They don't come with missile self-protection systems for fun.

Basic difference is training. A military pilot is trained to achieve assigned mission even if he has to endanger his life or aircraft, where as Civil pilot is trained to keep safety of his aircraft paramount as it has many other lives with him. Converting from Military flying to Civil Commercial flying, pilot finds it most difficult to adhere to follow strict safety regulations.

Welcome to aviation stackexchange. Ideally this answer could use some sources.

The last sentence is unadulterated nonsense. A disciplined military pilot can adapt to a different set of regulations without difficulty.

And many, many do...

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What do flight attendants do if a passenger asks what is going on in case of a potential emergency?
This is related to, but not the same as, another question I asked on Interpersonal Skills.
I was on a flight last year, on a route I fly on a fairly frequent basis. Shortly after takeoff, I heard the three double chime signal, which is commonly used by airlines to indicate to the crew of a potential problem. The crew quickly marched up to the front of the passenger cabin and was briefed by the pilots. I also noticed that the plane was going off course. Some time later, I used the onboard Wi-Fi service to query an online flight tracker about the flight I was on, and it said we were diverting back to our origin airport.
Throughout the whole incident, all the crew kept quiet about the whole thing, and didn't let passengers know about the diversion until just a few minutes before landing back at the origin airport.
Before the announcement, while the seat belt sign was turned off and while the crew weren't making any emergency preparations of any sort (just casually chatting with other passengers), I got up and asked the crew what was going on, and they said "nothing". I then showed them the tracker page which indicated the diversion, and they just asked me to return to my seat.
What's the general protocol for cabin crew, when asked by passengers who notice potential issues like this and get curious? Is it common for them to simply say that "nothing" is going on until the flight deck makes an announcement? What if a passenger really insists on knowing what's going on? (As an aviation enthusiast, I feel more comfortable if told about the issue; not knowing about it can make me feel tensed.)

Keeping hundreds people from getting nervous inside a confined space is the best thing the crew can do and they know it. If you, a passenger, is also an experienced airliner pilot there's not much you can do to help beyond helping the crew to keep the crowd cool

The way I see it, there is no reason for the flight crew to speculate as to what might be wrong. The captain or flight attendants will typically announce any information that is necessary for the passengers to know.

@jean Not a pilot, just an enthusiast, but I do see your point. After all, the top answers to the other IPS question I linked suggest exactly that.

By the way did you really find out what happen in the end?

@vasin1987 There was smoke detected in a lavatory, which was traced to a malfunctioning engine. The engine was repaired and tested, and the flight was ready to go.

Along the lines of @jean's comment, there's a Men in Black quote which continues to be infuriatingly useful to me: "A person is smart. People are dumb, panicky dangerous animals and you know it."

@selectstriker2 Umm... There are lots of reasons for the flight crew to figure out exactly what's going on. Knowing the condition of your aircraft is a pretty important part of flying it, especially in an emergency situation, as different types of problems need to be handled quite differently. I agree that there are less reasons for them to communicate that information to passengers, though.

@reirab I think there's some misunderstanding with my comment, and I probably should have used "flight attendants" rather than "flight crew". I agree that the pilots should absolutely figure out what is wrong. I don't think the flight attendants should be discussing what might be wrong with passengers, especially as they won't have the whole picture.

@selectstriker2 Oh, yes, on that I completely agree. Just as an FYI, "flight crew" refers specifically to the pilots (and, on older aircraft, flight engineer, navigator, etc.) "Cabin crew" is the term for flight attendants. FAs are crew, but they aren't "flight crew."

@selectstriker2 Don't worry; I made the same mistake on the first revision of this question; I had to edit it.

A diversion is not in & of itself anything remotely like "an emergency" nor a "potential emergency." Landing at the diversion airport is no different than landing at the destination airport - no additional risk whatsoever. So the 3 chimes notwithstanding, what you had was NOT a "potential emergency" in any way, shape, or form. That there was an issue with the bleed air system, which was evidently solved to the extent required for continued operation but which needed Mx attention, doesn't qualify either. So really, you're second-guessing the TIMING of the diversion announcement, no more.

What if a passenger really insists on knowing what's going on?

As always, it depends.
Let's briefly summarize the possibilities here:

Passenger spotted an issue which the crew is unaware of.
Passenger spotted an issue which the crew is aware of.
Passenger is behaving in a rude manner.

And let's go over the actions the flight crew can possibly take, without matching the above conditions:

Inform the pilots immediately.
Inform other cabin crew members.
Explain to the passenger what the issue is.
Warn the passenger to stop the behavior.
Ignore the issue altogether.

Now let's go over the scenario. The flight deck called for a briefing, so it is obvious that the pilots know what is going on. Every crew member was briefed as well. So that means scenario #2 on our first list, and we've ruled out #1 and #2 on the second list. They knew the plane is diverting, and they saw what they expected.
Action #3 is unlikely to end up well. When only individual passengers are informed about an abnormal situation, rumors would spread in the cabin, causing panic. It is even worse when the passenger thinks he is an "expert" when in reality he is spreading disinformation. Furthermore the flight attendants may not have complete information, they are only briefed by the pilots about the severity of the situation and what to do / not to do.
If the passenger really insists, perhaps a brief "The pilot is aware of the situation, please take your seat" would be the simplest reply. Beyond that, action #4 may be necessary. Cabin crew are trained for this, and there are procedures about how to deal with a passenger whose behavior is judged as unacceptable in flight.
So that leaves, #5. The pilots may make a PA explaining they have a technical issue and they are turning around. Or they may not, depending on the workload in the cockpit, severity of the situation etc. The senior flight attendant may, at their discretion, make an announcement informing the passengers they are going to divert. Or they may not.
What the pilots and cabin crew did, was kept the passengers calm, worked the checklists, and landed the airplane without incident. That's their job.

This should be asked as a separate question, but if the flight crew are aware of an emergency that is potentially fatal, do they have any obligation to inform passengers? This might be more appropriate for an ethics forum, the right to know of one's impending death, etc.

@user1997744 Cabin crew are also trained to handle emergencies. Their top priority is, obviously, ensure everyone has the best chance of survival. Details are too lengthy to discuss here, but yes, you can ask a separate question and it'd be on-topic for this site as far as aviation procedure goes.

@user1997744 haha, every flight is 'potentially fatal'. However, if the emergency was potential fatal, you wouldn't need the cabin crew to tell you. You'd probably notice an all-engine out, a fire or a stall without being told what it was.

Is there any evidence that passengers ever 'panic' when they learn there's a problem (other than obvious ones like a full blown fire in the cabin)?

Above the second list of choices, did you really mean flight crew, or did you mean cabin crew? "Flight crew" goes poorly with "inform the pilots".

What's the general protocol for cabin crew, when asked by passengers
  who notice potential issues like this and get curious?

The flight crew and pilots are under no obligation to inform the passengers about non critical issues and broadly speaking it's often better to provide only needed information so as not cause some kind of panic. In the vast majority of situations on an aircraft there is nothing the passenger can do other than evacuate when told to do so.
Turning an aircraft around and heading back to the point of origin is not necessarily an emergency although it can be there is nothing to say it is or is not from a passenger point of view.
Even if a passenger insists the cabin crew will likely ask them to take their seats, buckle up and await any further instructions. It's possible that the cabin crew is not even informed of anything as the pilots try and work the problem.

The later part of your question is answered here and the general answer is, unless you are a trained pilot it's hard to actually know if something is going wrong. There is a very interesting example of this from the Air Florida Flight 90 incident which is the only incident I know of where a non flying pilot spotted an issue and took action, this would be a fairly rare case;

Survivors of the crash indicated the trip over the runway was extremely rough, with
  survivor Joe Stiley – a businessman and private pilot – saying that he
  believed that they would not get airborne and would "fall off the end
  of the runway". When the plane became airborne, Stiley told his
  co-worker (and survivor) Nikki Felch to assume the crash position,
  with some nearby passengers following their example.

I misworded my question; I was thinking something else. I edited the question.

@gparyani i have added a second half to address the later part of the question which is more a less a dupe of this one

That "latter part" is more of a comment about myself than another question, but thanks for giving me the link.

It would be ill-advised to not tell the passengers you are turning around. The last thing you want is a rumor about the plane being taken over, fueled by the observations the plane is going the wrong direction and there wasn't any announcement.

Flight crew are the two in the cockpit. They would Aviate, Navigate and Communicate in that order. In large commercial plane they are separate from passenger by a cockpit door so they won’t know about your curiousity. Anyway their priority is the safety of flight, not to answer your question.
The cabin crew, on the other hand, may not know about what happen. They just know something is happening. Their job is to maintain order in the cabin. If they feel your action is against their job they may treat you as another problem and that is not a good thing.

Ah, sorry, I mistyped my question. I meant the latter paragraph.

This passenger would be second guessing the flight crew AND the cabin crew and insisting to them that they know better than them.
This passenger is going to be treated like the annoyance they are, told to go back to their seat and follow crew instructions.
They're not just obstructing the professionals from doing their jobs, this passenger is potentially causing serious harm by panicking other passengers.
If this passenger keep insisting on causing trouble, the  crew may well be forced to physically restrain them, with the help of any air marshals that may be on board.
If and when there's something the passengers need to know or do, they'll be told.

@ymb1 I think this does answer the question. Although the tone is rather aggressive, the answer boils down to "If the passenger who wants to know what's going on is causing a disturbance, they'll be dealt with like any other unruly passenger." Not a complete answer but I think it is an answer.

I feel this answer falls short of the standards of courtesy and respect that are expected here.

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Can anyone Identify this FLY FAIR seaplane?
This photograph, from my family's collection, of a high-winged, dual rotary engine, amphibious airplane, probably in the 1930's, appears to be an excursion plane at a fair since it has "FLY FAIR" written on the wing.  It appears to have the ID number of NC-155, or NC-156, or NC-158. It is difficult to recognize the last number.  I have searched and searched and not only cannot find other photos of this particular plane, but I can't find any photos of an identical plane.  I'm looking for Make, Model, and any additional information you may have. Your help is greatly appreciated.

Those are radial engines, not rotary.  If rotary, the cylinders would be blurred as much as the propellers are.

You are absolutely correct.  Either my typo or spell check.  I'm embarrassed I didn't catch that.  Thank you.

That is a Sikorsky S-38B
I am not sure about the registration. My guess is NC196H, but it is one out of this list:

NC158H,
NC159H,
NC195H,
NC196H,
NC197H,
NC198H,
NC199H,

See aircrafthistory.org.uk
The FLY FAIR marking may be a reference to the 1933/1934 Chicago World Fair / "A Century of Progress International Exposition". Jamiec found this photo album by George Buivid on auction that documents a trip to the Chicago World Fair in Sikorsky's own S-38 aircraft:

Picture source: Flyingclippers.com Artist: Mike Machat

source: Wikipedia original source: NACA Aircraft Circular No.79

You sure? The tail looks wrong to me (But the stubby biplane wings looks right).

@Jamiec, quite sure. The tail looks right to me. Can you explain in what way it looks wrong to you?

I wasn't sure I could see the double horizontal stabilizer, but perhaps just masked by the engines

Found this: https://s3-eu-west-1.amazonaws.com/antiquarianauctions/original/1582482461IMG_1746.jpg Might be a good addition/evidence from https://antiquarianauctions.com/lots/chicago-world-s-fair-photo-album-including-journey-to-the-fair-in-igor-sikorsky-s-seaplane

@Jamiec, nice find!

Thank you very much for your detailed answer.  And I believe you also have the location, the 1933/1934 Chicago World Fair. My family lived in the Chicago/Milwaukee/Madison area and I know they attended the Chicago World Fair from other photos we have.  Now I can make the connection.  I appreciate this very much. Combining your answer with the next detailed answer (below) and it appears to be the NC-158H.

The aircraft is clearly a Sikorsy S-38.  Looking at the aircraft's left wing, underside, far outboard, in the photo in the original question-- the first two digits in the registration number after the hyphen clearly appear to be "15" not "19". With a little less clarity, the third digit appears to be "8" or "B", not "9" or "6" or "5", and the last digit appears to be "H". So there you have it-- NC-158H or NC-15BH. The former coincides with one possibility out of a list 7 offered by this related answer to the same question, while the latter appears not to conform to the numbering system used in registration numbers beginning with "NC".
To see the image more clearly, a useful trick is to try tilting the computer screen up or down, or to raise or lower your head to change your line of vision to the screen-- this has a similar effect to adjusting the contrast of the photo.
Looking closely, we can also discern that the full text on the underside of the aircraft's right wing is "FLY AT THE FAIR", with the words "at" and "the" being in small print and stacked vertically one over the other.
One last note-- if we look carefully at how the bottom of the letter "F" in "FAIR" is mostly lost to view due to the curvature of the underside of the wing near the wingtip, this helps us see how the last character in the registration number is consistent with the letter "H".

Thank you for taking the time to decipher the NC number of this aircraft as well as your suggestions on how I can better determine numbers in the future.  Combining your answer with the research in the previous comment it appears to be NC-158H.  Thank you very much for your help.


text:
Can anyone help me with the Make, Model (version), and Unit of this WWII army trainer. Appears to be an AT-6 version
Location: Madison, WI Municipal Airport on May 21, 1939.
Notice the straight bottom on the vertical stabilizer, crest emblem, pitot tubes, landing gear, exhaust location, antenna, etc.
I have two photos of this plane, the 2nd photo is from the front, but I don't know how to add a second photo to this post.

I am interested in the second photo as well, mainly because the landing gear. I don't see any gear door on the wheels as I see in other BC-1's but also no wheel fairings as seen on most other NA-16 derivatives without retractable gear. I also expect an antenna (circular antenna) below the engine. If there is a limitation on the number of pictures new contributors can include in a question, can you try to write an answer and include it in there? I can then move it to the question for you.

Hi DeltaLima, My sincere appreciation for your response.  I found I actually have 2 more photos of this plane but cannot find how to post them.  I know it can be done because I received a response from another question where the comment included photos.  If anyone can teach me how to add photos, please do.  Having said that, yes, it has a circular antenna below the engine. The landing gear does not appear to be retractable. There is a protruding tube or antenna about 12" long and about 12" in from the tip of the right wing. Both wings appear to have landing lights. Exhaust is life side only.

DeltaLima - I think you nailed it with the NA BC-1 in that I've looked at several photos that match this plane except for the landing gear.  This plane definitely has fixed landing gear. Was there a model of the BC-1 that had fixed landing gear?  Also, I'm curious about the crest emblem on the side of the fuselage. P.S. It doesn't appear to be an NA-16 from all the photos I've seen.  Thank you again for your help.

as far as I know there was no BC-1 with fixed gear, but there also wasn't any fixed gear version with the rudder shaped like the one in your picture. It may have been an early prototype that ended up with the Technical Training command for the purpose of ... technical training.

Thank you, DeltaLima.  Your knowledge is exceptional.  I'm sorry I don't know how I can add my other two photos of this plane.  I tried to upload them in my original post and wasn't able to do it. I see no way to attach them later with a comment. Thank you again for all your help.  I feel it is not only important but necessary to have historical photos accurately labeled with as much information as possible. You have certainly enabled me to do that.

@FreshBreeze simply [edit] your post, place the cursor where you want the image to appear, then drag the other images into the edit box. The "add picture" dialog will automatically come up with the pic preloaded and all you have to do is hit "OK".

That is a North American NA-36, BC-1, a North American NA-16 derivative, the predecessor of the  North American T-6 Texan

Source: nationalmuseum.af.mil
Some observations that helped to determine the precise model:

The fuselage is covered with fabric. Later models used metal

The trailing edge of the rudder is rounded, later models had a straight rudder

The bottom corner of the rudder is squared, some other models are rounded (e.g BT-9)

The fuselage shows the crest of the USAAF's Technical Training Command:

Source: Picturing Meteorology. The text "Sustineo Alas" is latin for: "I sustain the wings", or more loosely translated: "I keep em flying"
The aircraft belonged likely to Chanute Field Technical Training Command (Illinois), located some 200 miles south of Madison.

You have amazing research and/or aircraft identification skills!

DeltaLima, I agree with Jamiec on your exceptional skills.  I believe you not only identified the aircraft but also its unit and home base.  I still find it interesting that the plane you posted is essentially identical even to include the position of the propeller, yours #31 vs mine #32, but yours has retractable landing gear and mine is fixed.  I wish I could add my two other photos so you could see them. Thank you VERY much for your research and identification.

P.S.  I have yet another plane I'd like ID'd, It is similar but is a biplane and I have failed to find a photo on the internet to help me identify it. I hope you will see my posted question and l look forward to your help if you see it.  Again, thank you for your assistance.

@FreshBreeze, you're welcome. Keep em coming!

This fine aircraft (according to the directors of many WWII aviation films) is the Messerschmitt Bf-109G
(Couldn't resist the joke, sorry)

Are you sure it isn't an AGM-Zero? I'm sure I saw it in a movie...


text:
This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff
This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff.
But for this example the engine is secured to a test mount, and under "full throttle", the thrust generated is still 130,000 lbs.  I believe that 80% of the thrust is from the fan itself.. but let's go ahead and assume 100% of the thrust is generated by the fan only.
If the large 12-foot ducted fan were instead connected by shaft to an external electric motor or gas engine, how much horsepower would be needed, to sufficiently spin the large ducted fan, to generate 130,000 pounds of thrust ?

FYI, there is no "GE90X" engine.  There is a GE90 and a GE9X.  The former is rated to 115klbf at takeoff, the later is just slightly less at 110k.  The GE9X does have the world record for thrust at 134,300 pounds, but that was on a test stand during a very unique test condition. Normal rated takeoff is less.

This is almost a duplicate of another question: What is the GE90-115b turbine power output in horsepower?
With the fan removed, and power used for e.g. ship propulsion or a power plant, the engine core can deliver about 66 MW or 90,000 horsepower continuously.
Takeoff thrust is higher than continuous, and the core does contribute some thrust. So to match 130,000 lbf, a fan this size would require external power in the range of 80-85 MW or about 110,000 hp.

Let's not look at what others have posted on the Interwebs but at physics: In this answer I describe how to calculate static thrust. That this is done for a propeller should not matter much: a fan is nothing more that a shrouded propeller with a high activity ratio.
So we have this equation relating power to thrust:
$$T_0 = \sqrt[\LARGE{3\:}]{P^2\cdot\eta_\text{fan}^2\cdot\pi\cdot \frac{d_\text{fan}^2}{2}\cdot\rho}$$
which can be written as:
$$P^2 = \frac{T_0^3}{\eta_\text{fan}^2\cdot\pi\cdot \frac{d_\text{fan}^2}{2}\cdot\rho}$$
Using proper SI units, we have $\rho$ = 1.225 kg/m³, $T_0$ = 578.27 kN and $d_\text{fan}$ = 3.4 m. The efficiency $\eta_\text{fan}$ must be guessed at this point - propellers have less than 50% in the static case. With those 50% the power required is indeed 66 MW. However, it is fair to assume that the GE90 fan has a lower efficiency than a lossless propeller, so the required power of this hypothetical electric motor should be closer to 80 MW which confirms @Therac's answer.


text:
Question about the difficulty of a couple of airplane maneuvers
I have a hypothetical scenario and I was wondering if any experts might be able to speak to it.  I will lay out the scenario, with a couple of specific questions, and maybe some honest answers will come if I leave out the dog whistle words :)

A plane is travelling at 322 Knots at 6800 feet and wants to simply
point the nose down and hit the ground somewhere within a target of
34 acres.

A plane is traveling at 336 knots at 6800 feet and begins a spiral
decent reducing speed over the next 2'40" completing a 270º turn,
coming out of the turn at 2200 feet.  The radius of the descending
circle at about 2.75 miles.

From the altitude of 2200 feet, travelling at 312 knots, said plane
increases speed over the next 40" finishing at the wall of a great
invisible barrier going 488knots, just five feet of the ground. The
descent rate increases exponentially beginning at 3200ft per minute
until getting to 5800 feet per minute travelling from 418 to 488
knots from 1200 feet to 5 feet in 12 seconds.

How easy or difficult would any of these maneuvers be to undertake, say in a Boeing 757, for a pilot who

had just been hired by a major airline?
Has several 1000 hours of flying experience
Could fly a Cessna if someone sat next to her to watch in case things went south (literally).

A sincere thank you - while this post may seem to have some snark, it is asked with 100% intellectual sincerity.

Calvin

These are oddly specific numbers... why? The pentagon is 34 acres in size and this matches a lot of details from the aircraft that hit the Pentagon on 9/11... Conspiracy theory?

Any pilot past their Commercial Pilot Certificate training (250 hours of flight time) should be able to hit a point on a runway roughly 10,000 square feet (100’ x 100’). Especially if they were not trying to make the landing as smooth as butter. If you are trying to discern whether a ragtag group of extremist could do it, the answer is yes. Could someone with absolutely no aviation experience do it? Maybe with coaching. Especially if they do not know or have any concerns with not damaging the aircraft during high G maneuvers.

But note that 34 acres could also be one inch wide and really long, in which case it's no longer possible to land any reasonable aircraft "inside" it.

I’m voting to close this question because this question appears to belong on terrorism stack exchange

If this is truly out of intellectual sincerity, I recommend downloading the Airplane Flying Handbook from the FAA for free. Then, research: Commercial Standard Steep Turns up to but not including 60° of bank; Emergency Descents; Short Field Landings; Teardrop 270 Descent Entry into a Traffic a pattern. Etc.

@JerryCoffin - Actually, there was no criteria that the entire aircraft needs to be within the 34 acres. In which case, it should be easier to hit the target.

If you don't care about keeping the airplane intact flying becomes much more accessible to the untrained.

A runway at a decent size commercial airport is ~200' wide and 10,000` long, which is about 2 million square feet or 45 acres, most of this is for roll out can pilots generally have no issue touching down in the first 1000 feet which covers an area just under 4.6 acres.
So its safe to say that a pilot can maneuver a plane from 6800 feet down to a landmass of 34 acres.
A turn of that as described could be achieved with a ~30 degree bank, that decent rate is fast but not unachievable.
Aggressive decent rates like this would likely not be possible in a 757 but low and fast is not out of the question for some planes

Any airline pilot (fresh in or about to retire) should be able to pull off the first two maneuvers with out an issue . A decent CFI would likely be able to coach someone threw these maneuvers if they were just starting out. As for the last maneuver, your gonna need a G Suit....

Great answer. But, you may not need a G-suit for the last maneuver. Suicide can be assumed in this scenario. A G-suit would be arbitrary since consciousness may not be necessary in the last 60 seconds. If suicide was not the goal and a G-suit was worn, the speed and altitude would be ill-advised.


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Is Sonex a good trainer plane?
Hello I am thinking about buying a Sonex to start to learn how to fly. I want to know, if it is a good plane to learn in?

You might want to compare the characteristics of the Sonex aircraft to the criteria here: http://aviation.stackexchange.com/questions/3432/what-are-the-properties-of-a-good-general-aviation-training-aircraft

I would avoid the Sonex, or any other kit aircraft, until you have some student flight time under your belt and are sure that's the way you want to go.
The problems with using a kit LSA to learn include:

The "Build then fly" process of a kit without a license assumes you will want to do the latter after doing the former. Plenty of novice pilots spend 5 to 10 hours at the yoke and either get it out of their system and lose interest, or wash out in other ways (fail medical, can't pass written tests or checkrides and give up, run out of money to spend on rentals and fuel). If that happens to you, you'll be stuck with a kit you bought new, which you can't fly and now have to sell used. It's better to rent your way through the first few weekends as a student, then once you have your student cert, a few flight hours, solo endorsement and you're sure you are able and want to keep going toward a sport or private cert, you can look for an aircraft to own and practice with.
Building a kit means getting that kit certified airworthy. An amateur-built plane has to go through a rigorous mechanical inspection before you'll be allowed to take it up in the air. The fact that it's a kit for an aircraft fitting the "light sport" type rating might make it a little easier, but they might treat it as an "experimental" craft just because it's a homebuilt and go through the "Special Airworthiness Certification" process for those types of planes.
Buying someone else's kit means inheriting their mistakes. If you don't build, and instead buy a kit plane that someone else went through the trouble of building and getting certified, you're still flying a homebuilt. Anything the FAA inspector missed could cause a failure in flight, and you can't just pull over and call a tow truck when that happens. The same could be said of your own homebuilt, and overall with the strict mechanical inspection criteria of planes this isn't as big a problem buying a plane versus buying a used car, but it's something to think about; they built and configured it their way, and if that's not "your" way or even the "usual" way it can be distracting in flight, and distracting is dangerous.
The Light Sport class is designed for day VFR with a limited range. If all you want is a sport pilot certificate to go out flying in fair weather near your home airstrip, great, grab an LSA like the Sonex and have fun. If you want to progress to a PPL, and fly cross-country, at night or in IMC with your instrument rating, you'll need a plane capable of flying in such conditions for your checkride and other training time including at least one serious cross-country flight. The stock Sonex builds I'm looking at now do not have the IFR "big 6" and really no room to mount them. You can go glass, but instrumentation's only one piece of the puzzle; you'd also need an external light kit which doesn't come stock, and the airframe has to be rated for flight in minimum winds as well as IMC like rain, which most LSAs simply are not designed for.
LSAs have limited power by design. That doesn't mean other aircraft don't have similar power ratings (the stock Cessna 150 is only 100hp while there's an engine kit for the Sonex providing 120), but the Sport Pilot license was designed for flying LSAs with a max power of 87hp, with an instructor endorsement required to fly anything more powerful. Just one more hurdle to getting rated to fly your own up-engined Sonex (or anything else besides).

Just my analysis. Again, if you just want to start with a SPL (20 hours flight time, some ground instruction and a written test, no medical beyond the basics for a driver license) and see where it goes from there, then a Sonex kit, base price about 18 grand, is a pretty good deal assuming you're good with tools. But if you want to progress to where flying is useful beyond simple recreation, you'll start rubbing up against the limitations of an LSA sooner than you would in a more full-featured trainer. That more full-featured trainer is also going to be more expensive, but it'll be a plane you can use much further into your flying career, and if you take care of it, will hold cash value and even match inflation so you can use it as a store of value to trade up (the 150's original retail price back in the 60s was around \$7500; those same '60s airframes change hands at around \$25,000 now).

Re: Light Sport aircraft & Night/IFR operations, there's nothing in the regs prohibiting this: It just needs to be appropriately equipped & approved by the manufacturer for the kind of operation being conducted (as the builder of a kit you're the "manufacturer" and can approve the aircraft for those operations). I'm not sure the Sonex would be the ideal platform for that but other kit-built LSAs might be (N717WR from that gallery is IFR equipped).

…as you pointed out though there are certificated options (Legacy LSAs) that may also fit the bill: You can't go wrong with a Cessna 150 & basic IFR equipment.

@voretaq7 - You're right that there's nothing preventing an LSA class from being equipped for night/IFR operation, or even cross-country assuming it has the fuel capacity. However, these aircraft are designed to be flown with a Sport Pilot License, which is relatively easy to get but places a lot of restrictions on the pilot. Some can be overcome by endorsement, others cannot. So, the primary market for an LSA is a pilot who would not be allowed to make full use of a plane capable of XC/IFR/night flight and that reduces the importance of equipping the planes in this way.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Why are aircraft windshields not unbreakable?

From a materials engineering standpoint, cockpit windshields,
  typically weighing between 25-40 pounds, depending on the type of
  windshield build, are typically constructed of several layers:
(1) A glass face-plate, roughly 1/10" thick;
(2) A Polyvinyl Butryal (PVB) layer, about 1/8" thick;
(3) A stretched acrylic layer, approximately 1" thick;
(4) An additional PVB layer, nearly 1/10" thick;
(5) An additional stretched acrylic layer, approximately 1" thick. Source

But even then, it is not unbreakable. We have had several cases of broken windshields, as mentioned in above source. Also, the co-pilot  in Varig Flight 254 crash was wounded from a tree, which struck his shoulder after crash landing.
So, why are aircraft windshields not made from unbreakable Glass Ceramics ?

Simple: glass ceramics are not unbreakable. Furthermore, being a ceramic, it will shatter instead of break the way safety glass does.

There is no such thing as "unbreakable" so I don't understand what you're asking.

and even if there were the cost and weight penalties would be too high.

Windshields
In the US, aircraft windshields must conform to 14 CFR 25.775 - Windshields and windows

(b) Windshield panes directly in front of the pilots in the normal conduct of their duties, and the supporting structures for these panes, must withstand, without penetration, the impact of a four-pound bird when the velocity of the airplane (relative to the bird along the airplane's flight path) is equal to the value of V C, at sea level, selected under § 25.335(a).

So, windshields are not indestructible partly because they are not required to be.
I guess windshields are not required to be indestructible because bodies like the FAA probably take the view that when an aircraft impacts a massive object at high speed, say a large mountain at 500 MPH, it is of no consequence whether the windshield survives intact at the bottom of a large crater of tiny aircraft fragments. It serves little purpose to make the windshield substantially stronger than the surrounding airframe.
Glass-Ceramics
Glass Ceramics are not unbreakable. For example a glass-ceramic might have a bending strength of 340 MPa (Ref p9)

Thanks! Just for fun, the only natural choice for windshields would be Aluminium oxynitride (ALON) better known as transparent aluminium from Star Trek IV (aye captain!). https://en.wikipedia.org/wiki/Aluminium_oxynitride


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What difficulties would would a person face, trying to use a Cessna as a car?
The older  Cessna's (like 172,152) have an average wing span of about 10m, which would need about 2 lanes of some highway or some other road and would be easily available on some National Highway. The taxiing speed that Cessna can achieve is pretty decent. So, what problems would a person face trying to use a Cessna as a Car, one of them could be space, but what are some other problems, barring any regulatory/legal issues? Mainly I am demanding an answer from fuel, speed, and safety point of view.

I would look at the mileage the costly ATF is giving me, plus would it meet the emission guidelines set for road cars?

The regulatory/legal issues are the difficulties. If you can ignore them completely then in theory you can drive anything that moves, no matter how dangerous, expensive, impractical or just ridiculous it is. I'm not sure what answer you expect here, but if you have a specific reason or background for asking then please add it, it might help to get answers.

i suspect the propeller violates some number of safety standards as well -- cars are supposed to be designed to minimize risks to pedestrians in a n accident, and a propeller also does that.

Here is an article about an australian who drived his plane to a near pub: http://www.theguardian.com/australia-news/2014/nov/03/australian-man-drives-plane-down-main-street-drink-pub

@mins Sure there is! You'd just need to flip the switch at regular enough intervals. Minor retrofitting may be required.

@mins and how do you merge them?

Even assuming there is room - wings and the propellor could quite easily hit something or a pedestrian not looking where they were going... etc etc. An aeroplane is quite difficult to steer on the ground because the flight controls don't work very well if at all at low speeds - you use the steerable nosewheel which is connected to the rudder pedals and also the brakes (one on each rudder pedal that affect the main wheels).
Due to the large areas of body and not least the wings and tail it would be affected by winds at street corners for example. It would have to keep its speed fairly low (10-20mph). Any faster and it would be very stressful for the pilot and quite easy to lose control of it. It would also be difficult to judge clearances from other objects at higher speeds. Cars don't have wings stuck out 15 feet either side of the driver!
Having said that I am sure it is far easier to drive an aeroplane on the ground than it is a car in the air!

An airplane is not all that difficult to steer on the ground, particularly something like a Cessna 152 or 172 (steerable nose wheel, differential braking). The suspension and tires however are hardly roadworthy: You wouldn't be able to take curves at the posted speed limits, much less the speeds people normally drive.

Sure I agree with you, I was trying to compare it to the ease of driving a car. Now if it was a taildragger that would be a different story alltogether..

There are other things I've thought of, like the road would have to be smooth, the engine would be idling for long periods and the plugs would get lead deposits on them (it would do 10-20mph at a very low power setting), you would have to slow right down for corners to avoid tipping over, and finally the brakes would overheat after a few uses because they are small compared to a cars and not designed to be used on the ground too much. Not sure about fuel consumption it doesn't sound too efficient, although fuel consumption is similar to a SUV when in the air. Hope this answers your question!


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What is the average time taken to load and unload the luggage?
I was wondering, how are Lufthansa able to unload luggage (LH 760) of 500 passengers and load the luggage (LH 761) of another 500 passengers, in just a 2 hour gap for return leg of 7000 KM FRA-DEL journey.
What is the average time taken to complete a typical loading and unloading operation for a fully loaded A380? Some simple maths in this case shows its about 14.4 seconds for unloading and loading, pretty very high.  But that's assuming that no time is spent in any  task other than handling luggage, which is pretty foolish.
Bonus Question : How are the handlers able to complete this operation that fast?

Because the bags are not handled one-by-one.  They come out in a container which is loaded, and unloaded, directly to the aircraft full of bags.

In many (if not all) airliners, there are multiple luggages bay. You may load/unload them independently and simultaneously (given you have enough workers). Not to mention ULD and self-loading fret using multiple jetways while the luggages are handle (possible as they are not using the same doors)

Another Airbus document mentions (on page 188, section 5-2-1) full load of A380 as

FWD cargo compartment: 20 containers
AFT cargo compartment: 16 containers
Bulk cargo compartment: 1,000 kg (2,205 lb).

and rate of loading and unloading as

Container unloading/loading times:

Unloading = 1.2 min/container
Loading = 1.4 min/container.
  Bulk unloading/loading times:
Unloading = 110 kg/min (243 lb/min)
Loading = 95 kg/min (209 lb/min).

From this calculation best case is they can finish unloading and loading within just above 30 minutes. However this is not possible since there will be some delay due to the fact that there are other things to be done during turn around that may disrupt exchange of cargo. Also other services such as cleaning need to be done during turn around time.
Airbus provides 2 scenarios for turn around time
 - 90 minutes if both decks are serviced at the same time.
 - 140 minutes if both decks are serviced only from the main deck.

Passengers' luggage is not loaded in an A380 by one suitcase at a time. That would be very time consuming.
After passengers check in the luggage and head towards the gate where the superjumbo is parked, their baggage is started to get stored in unit load devices1. And after that, those ULDs are loaded into the airplane:

Image Source
According to Airbus, the A380 can store 38 LD3s. Volume of a typical suitcase/bag (dimensions: 32"H x 12"W x 21"D) is less than 5 cubic feet, so 30 suitcases can easily fit in a single LD3.

Now let's talk about your questions about loading and unloading times. As A380s mostly fly on international routes, passengers are required to check in several hours before a flight's departure. But once they check in their luggage, the process of loading those LD3 starts, even if the airplane has not yet arrived at the gate. As soon as the airplane reaches the gate, unloading and loading processes start. These two processes are not as time consuming as they may appear2.
Passengers' checked in luggage is not loaded like in this manner (picture below). On a wide-body like an A380, this is the case of carry-on baggage which stored in the underfloor area, instead of overhead bins.

Image Source

1: A380 uses LD3, whose capacity is 159 cubic feet.
2: Note that after an LD3 is unloaded from an airplane, it might take another hour or even more for the passengers to get their luggage at the baggage claim area.

Nice detailed and illustrated answer.

accepting the other answer just because it answers the main point of time taken...


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Why are the cabin chimes one semitone lower on the Boeing 747-400 than on other aircraft?
I noticed that the cabin chimes on the Boeing 747-400 overall sound one semitone lower than on other aircraft, including the 737, 777, Airbus A320, and even the 747-8. The same semitone-lower chimes are used on the Bombardier Q400, but that was built later.
Notice here that with the exception of some Qatar Airways planes using the "high" chime instead of the "low" chime for the seat belt sign, all the "low" chimes sound the same, with the exception of the Bombardier Q400. That chime is the same as the one on the Boeing 747-400.
Why is this the case?
Update: I noticed that this question was marked as being primarily based on opinions. However, it's not based on opinions. If you looked at the video links I supplied above, it is a fact that the cabin chimes on the 747-400 are lower-pitched than most other planes. All of the planes in the compilation video, except one, are at the same higher pitch. It's not just my opinion that they're lower-pitched. Also, if the answer is that "the chime manufacturer simply built it that way", that should be an answer. Questions shouldn't be closed based on the answer, the merits of the question alone should be judged.

You realize that there is no standardization for these tones and they can differ by manufacturer and model. They can even differ by operator...

Obligatory Fawlty Towers: "the fire bell is a different; it's a semitone higher"

A born skill known as a "perfect pitch" is required to hear a semitone difference for the single, randomly sounded tone. Not even every professional musician can do. Most people can only tell the difference between the two that sounded very recently.

I work for a company that makes such a chime and I can tell you that manufacturing tolerances amongst components in the circuit play a part.  I don't think there is a rigid specification for this either.

In the compilation video, the chimes are all the same note except for the dash 8 Q400, which is a minor second below the rest, and the 787-800, which is a minor third above the rest.  However, the video for the 747-400 is from a flight simulator, which should not be considered definitive.

@WayneConrad I can confirm that every 747-400 I've flown has the exact same chime that is featured in the simulator video, down to the mechanical characteristics of the chime, having flown on that plane so many times. Unfortunately, I couldn't find a video where someone recorded the seat belt chime like the compilation, so I linked to this one instead.

The pitch also depends on the the original video footage's FPS (frames per second). A 24fps video played at 25fps would have a higher pitch than originally recorded. On top of that you can add qualitative differences between recording devices and variations due to different video/audio encodings and conversions.

@rainbowtableturner The videos are all being played at their original frame rate, and I can tell from having flown on 747s and other aircraft so many times that the chimes shown in the videos are the same as those in real life. That said, I'll later publish some analysis that more clearly shows the difference.


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What button did a pilot press that led to them being caught for falsifying experience?
I just saw this Newsweek article, Man Pilots Planes for 2 Years After Lying to Airlines About Experience:

A man has been sentenced to one year in prison for lying about his job experience before working as a commercial pilot in the U.K. for two years.
Craig Butfoy, 49, entered false details and fabricated his experience in his flight logbook so that he could appear more qualified to work for BA CityFlyer, a British Airways regional airline, and former Irish regional airline Stobart Air.

To summarize, a pilot for a major British regional airline was caught falsifying his flight hours and certifications to get his job.
What's interesting to me is, according to the article, how he was eventually caught:

Butfoy was employed with each airline [BA CityFlyer and Stobart Air] for one year, from 2016 to 2018, according to The Times of London. During that time, officials at BA CityFlyer reportedly became suspicious of his experience after an incident occurred in Switzerland when he pressed a button that "no qualified pilot would," a source told the news outlet.

What button(s) exist(s) on the sole aircraft type BA CityFlyer operated at the time, the Embraer E-Jet family (the 170 and 190SR, to be specific), which "no qualified pilot" would press, and which one was pressed by the pilot? Why would pressing that button be considered an action worthy of starting an investigation, which would eventually result in the airline finding out he made false representations?

I'll try to salvage the question by editing. Original title was "What button did a pilot press that led to them being caught for falsifying experience?", which is unknown. But a producing a list of such switches, perhaps ones that have been activated by mistake due to inexperience, may be feasible.

Just a though: do not rush to VTC even though it seems from ones perspective that a Q is not answerable. Perfect case example here...

Comments are not for extended discussion; this conversation has been moved to chat.

There appear to be conflicting reports of what exactly happened. A relatively detailed one says the pilot has accidentally cut power to the aircraft, while sitting on the tarmac. This has been mentioned by The Telegraph.

But suspicions concerning Butfoy's performance were roused when he apparently plunged a jet into darkness while stationed at an airport in France, the Telegraph understands.

There is more than one way to lose power. One example scenario that involves specifically a button rather than a switch:

The pretender starts the APU by mistake, while ground power is connected and sufficient.
Their mistake is pointed out by the other pilot.
The pretender turns the APU off, but it keeps running, which is by design.
In a haste to fix the mistake, they push the APU Emergency Stop button, next to the knob.
Since starting the APU disconnects AC ground power on the type, the plane goes dark.

This is something that no qualified, type-rated pilot would do. They would know the correct power transfer procedure. But this kind of behavior differs between types.
It's these procedural details of how the systems work that one can't just wing, and only a pretender would try. A panic shutdown instantly outs someone as a fraud, it's a "where did you get the uniform?" kind of blunder.
There are other ways to get the same outcome, and most involve a switch flipped or a button pressed at the wrong time. Since pilots are human, such mistakes happen. Doing something totally out of place for a practical reason, however, would grab attention.
Shutting down an airliner can delay the flight, lose money, produce passenger complaints. It's not a reportable incident, since it doesn't affect safety, but it's good diligence to run an investigation internally. The company would mostly be looking to see if something similar happened before with previous employers, rather than for outright fraud.

That article says France, but my article says Switzerland. Why do they report different countries?

The APU Emergency Stop button exists, and given that it exists, it is meant to be pushed, no? Presumably by a qualified pilot? Of course the idea is that there would be some reason they would push it, but why do you say no qualified pilot would ever do it?

@randomhead Every button is meant to be pushed under some circumstance. But pushing something completely pointless can be dismissed as an accidental touch. One would out themselves as a fraud by doing the wrong thing for a valid reason. Turning the APU on by mistake, then shutting it off with EMER STOP would be one way. Note that I don't know what happened, it's just an example.

Here's the same question, asked on reddit's /r/flying. More discussion can be found there.

@Therac : for the sake of this example, should we understand it so that a competent pilot, after activating the APU by mistake, should know what procedure to use to deactivate it, instead of pressing the emergency stop?

@vsz Yes, in this example. Since turning the APU knob back to off won't shut it down at once, it's possible that someone unqualified would resort to emergency stop. While a type-rated pilot would follow the power transfer procedure to go back to GPU without going dark. I'll edit a bit.

@gparyani Basel and Geneve are airports in Switzerland. And in France, since they have direct exit to France and Switzerland ...

Kelsey at 74 Gear covered a "wrong button" on his youtube channel. Not saying it was any of these incidents, but interesting timing. (TLDW: he hit the PTT button?)

It was probably not a single act.  The button press was probably a "straw that broke the camel's back" event that was the culmination of a string of suspicious and odd events that finally led someone's BS detector alarm to trip over the threshold.
It's not that hard to goose your qualifications as long as you have the basic difficult-to-forge official documents like licenses etc and you don't get carried away with it.  Nobody is going to audit your log book, going back years looking for "P-51 time" (a old slang word for fake hours), beyond calling references and previous employers, and someone who is really clever and resourceful will be able to pull it off to a point.
There is quite a lot of reliance on the interview process to weed out phonies, followed by simulator training and evaluations as another filter, with line indoctrination as a final filter.  It would be a clever person indeed who made it that far before they finally screwed up badly enough to get colleagues taking steps to trigger an investigation.

"P-51 time" is an old expression for time added to a logbook by a Parker model 51 pen. (ie. faked hours)

Yeah kind of a double entendre gag. Common expression when I was young, although I hadn't heard Americans use it.

According to the news source, the airline only "became suspicious" after the button press incident occurred in Switzerland.

At the management level. Someone had to report it to them.  At the crew level, there were probably "observations" and internal gossip for a period of time but it took some really egregious event to finally make someone report the guy

Its quite surprising that the pilot made it that far and didn't bother to master the plane they're supposed to be flying.

@JonathanReez maybe they did... but only when everything is going according to plan. You wouldn't get much practice with emergencies or mistakes that way...

@JonathanReez He probably did a great deal of practice, in Microsoft Flightsim... While that can get you quite able to fly a specific plane under normal conditions, it won't get you fully familiar with things like unusual manouvers, emergency procedures and every single button/switch (and corner-cases of their usage).

Absolutely.  With an add-on like the Majestic Dash 8 or similar sims with that level of detail and sophistication, and an operating manual, you can give yourself a type rating.

@A.I.Breveleri In the same sense, there's the "bravo india charlie" registration.


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Can any modern commercial airliner currently in service take off vertically?
I saw a video of a Boeing 787 taking off 'vertically' at the Paris Air Show.
How is that even possible? It was to my prior knowledge that only fighter jets had the capability and maneuverability to take off vertically. Is the illusion that the 787 taking off vertically achieved by camera angles?
Be that as it may, the question has to be asked; does any commercial airliner currently in service have the ability to take off vertically?

A Boeing 787 performing a 'vertical takeoff'

That's not nearly vertical! See also: Could the Boeing 787-9 near vertical takeoff demonstration be performed by Airbus A350 aircraft?

I'm asking whether a commercial airliner can take off vertically, not specifically regarding the B787

Downvoted for improper use of the term vertical.

@MichaelHall You shouldn't downvote the OP for questioning something that is broadcasted by marketing and press.

@bogle, Boeing markets the 787 with vertical takeoff capability?  Please provide a reference.

@bogl, and from the camera angle in the linked video it is possible that it momentarily hit 90 degrees nose up.  However, the photo in the question is labeled "vertical takeoff", but the climb angle is obviously only about halfway there.

My point is that the photo is labeled incorrectly.  Yes I read the question.  I understand that the OP also references a video, this fact does not negate the incorrect labeling of the photo.  Yes I read your answer, and it was a good one.  Anything else?

ummm, the OP themselves voted to close this... why is it being VtR?

No commercial airliner can take off vertically.
The B787 in your image is not ascending vertically either. Just from the image, I would guess the attitude is about 45 degrees.
As you write, the picture was taken at an airshow. The aircraft was empty and had a lot of spare power to show off.
Besides that, vertical take off means to leave ground without any horizontal speed. Certainly the B787 didn't do that.

The angle shown in that photo is about 45 degrees, far from being vertical.
This is a demonstration flight, where the aircraft is nearly empty (probably a light fuel load as well), so it's at about half its MTOW.
The aircraft takes off horizontally, gathering speed along the runway as usual. Then it pulls up in a climb that briefly reaches a high pitch angle, until a stall warning prompts the pilot to reduce his pitch angle. The aircraft can't sustain this for long (the power/weight ratio isn't enough to do that).
I suspect he's also flying at a high angle of attack (i.e. the nose is higher than the angle of his flight path), making the maneuver look more spectacular.
There are aircraft that can pull the nose up into a vertical climb: modern fighters have the 1:1 thrust/weight ratio needed to sustain this. Airliners don't: a 1:1 T/W ratio is overkill for an airliner (the B787 has about 1:4 at full load) which would make the aircraft unnecessarily expensive to operate.

A bit of terminology confusion here. There is a difference between a Vertical Takeoff And Landing like one done by the V-22 Osprey, and a vertical climb done by an aerobatic plane or a military fighter. No commercial airliner can achieve VTOL. No commercial airliner has the thrust to weight ratio to maintain a vertical climb for long, neither. In the promotional videos from Boeing, their test pilots go near vertical for seconds before they have to lower the nose in order to prevent a stall.


text:
Why don't commercial aircraft use tail hook technology?
Tail hooks help drastically reduce an aircraft's speed during landing, and would therefore reduce the necessity of having long runways.
So why doesn't tail hook technology be implemented into commercial aircraft?

How much would a tail hook landing increase passenger discomfort? How much cost does tail hook systems everywhere compare to building a longer runway? What happens if the runway cable system were to fail or it was missed? What happens if the aircraft's tail hook system were to fail? How much more maintenance would cable systems require over some more concrete? How much stronger would cable systems need to be over say an aircraft carrier situation with little light(-ish) planes?

Related: Could airliners use a steam or electric powered catapult for take-off?

A tailhook does not prevent you from building existing infrastructures (e.g. long runways) as it may fail to deploy and you don't want to close an airport because one ground infrastructure is inoperative (note that you can still operate an airport without ILS, you just have to modify minimums and separation)

Because passengers really don't like enduring that kind of deceleration on landing. Scares them. Injures them. And if Junior is playing with his seatbelt latch at the wrong moment, there's a real risk of a fatal injury.
And because you still need the runways for any aircraft not equipped with this equipment, and for takeoffs.
If the Air Force doesn't want to equip all their jets with the equipment (weight, cost, complexity) involved with arrested landings, the chance that the world of civil aviation will want to is roughly zero point zero zero.

Nice answer. Just as a short addition: Maximum Autobreak usage on an airliner is already something your average passenger does not appreciate too much.

The aircraft that the Navy uses to fly passengers to aircraft carriers, the Grumman C-2 Greyhound, has the seats facing the tail.  I'm not saying that the public would tolerate the strong deceleration, but facing aft helps quite a bit.  Of course changing airliner seats to face aft would itself be quite unpopular with the flying public, and probably increase air sickness.

Weight and cost.
A tailhook landing puts a great deal of stress on an airframe, airplane structures would have to be reinforced along the frame to distribute the force across it and hold together. Airplane passenger seats would need 4 or 5 point safety harnesses to keep the passengers from getting injured on landing. All that adds weight, which reduces payload capacity, and makes planes and plane fares much more expensive.
The arresting gear isn't free, and you need 2 sets per strip. An airport with 2 landing strips will need 4 sets of arresting gear with multiple wires. This would cost millions to install and maintain. Runways are much cheaper.
Plus, what will an airplane do if it fails to catch a wire? It can power up and take off again, if it has enough runway space to do so.
Oh, and how will the airplane take off in the first place? It has to have enough runway to do so, unless you plan to install rocket assisted take-off systems or afterburners to commercial jets.

In addition, to withstand carrier landings, planes with tail hooks have to be very stoutly constructed. This reduces their useful payload, something that commercial carriers want to avoid.

I don't know if you've seen videos of aircraft carrier landings, but:
1) They have to slam the aircraft into the ground to guarantee the hook will connect. The G forces from this and the subsequent rapid deceleration are too high for your grandma to cope with, so passenger numbers will fall, seatbelts need to be redesigned, and landing gear strengthened.
2) In case the cable breaks the pilots engage full throttle before touchdown so they can takeoff again, until the aircraft has stopped. Commercial aircraft do not have the thrust/weight ratio to takeoff in such a short distance from a reduced speed so a cable break will result in an overrun and possibly death.
3) The cost of all of this vastly outweighs the tiny benefit of having shorter runways.

Point 2 is not really correct. The aircraft already has the speed needed to lift off again, so it can rotate immediately if it misses the wire. The C-2 Greyhound used for transporting cargo and personnel to aircraft carriers does not have significantly higher thrust/weight ratio than other cargo aircraft. It is much sturdier though, of course.


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Is there a minimum speed requirement for military transport aircraft?
I understand and military cargo/soldier transport aircraft are not as agile and fast as fighter jets, but I was wondering whether one had a minimum speed requirement to be able to become a 'military aircraft'.
I'm wondering this because speed can enhance the speed at which operations are executed, and avoid enemy aircraft or missiles. It's simply not safe to have an aircraft moving at a speed in which they can be shot out of the sky in a matter of seconds.
Note: excluding helicopters

The old military gliders were technically transport aircraft, and they were really slow with an incredibly short (independent) range.

Military transport helicopters are often required to hover at zero airspeed. How slow do you want to go and why?

Kawasaki C-2 had a minimum cruise speed requirement. And it seems that some other newer military transports also do 0.8 Mach cruise that matches commercial airliners. It apparently makes air traffic control easier which allows more optimal flight paths or something. So there can be speed requirements during design and 0.8M seems popular right now. (No, I did not really look that hard, so might be totally wrong.)

@Ville Niemi: But that's requirements for particular aircraft, not in general.  E.g. the C-5 Galaxy is designed to cruise at similar speeds to commercial air traffic, but the C-130 cruises around 210-250 kts, the V-22 Osprey is around 270 kts, and so on.  Really depends on the aircraft mission.

Do you mean stall speed?

@VilleNiemi The C-17 doesn't cruise at anything like Mach 0.80.

The premise of this question is utterly confused & mistaken. Avoiding SAMs isn't about outrunning them at all, except arguably in the case of the SR-71. Plenty of military aircraft are notably slower than commercial jets: C-12, T-6, T-44, C-130, P-3, E-2,C-2, C-160, etc. All of these are absolutely military aircraft, even though they'd all have trouble outrunning missiles much bigger than a large Estes rocket. (slight hyperbole, acknowledged)

@RalphJ I know and neither do lots of other transport in use. In fact it is only the newest design (I think) where the speed has been considered important.

@jamesqf Obviously. Was that not clear from my comment?

@Ville Niemi: Obviously not, or I wouldn't have bothered to add my comment :-)

Not sure why the down votes. The question is based on misconceptions, but so many questions here are, that certainly can't be a close reason. It's not an exceptionally good question, but I don't think it justifies being down voted to oblivion. Anyone care to explain?

@jamesqf Still not seeing it but being as Ralph J seems to have also misunderstood the same way it is probably my mistake. Since I know what I am trying to say, I cannot really see how clear I am being.

There is no special certification that gives out the title of a "military aircraft". Any aircraft that is owned and operated by the military is, thus, a military aircraft.
Even the fastest aircraft can be easily shot down by modern missiles. For fighters, missile evasion is more about turn rate than speed, and for large non-combat aircraft, countermeasures are used. Speed is dictated by mission requirements instead.
The Antonov An-2 is operated by at least 50 national militaries around the world - more than the F-16 - which makes it one of the most-widespread military aircraft. It's popular with militaries for its ruggedness and rough field capabilities, and thousands have been built for military use.
It also happens to hold a solid standing on lists of the slowest production airplanes, with a top speed of just 140 knots and no specified stall speed. Few factory-built fixed-wing aircraft are slower, and they're all considerably smaller.
Being manned, fixed-wing, powered, mass-produced, and employed operationally, not for training, it ticks all the boxes to count as a military transport aircraft, without any small print. That should be example enough to make the answer clear: there isn't. Military aircraft can be as fast or as slow as the mission requires.


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Are there aircraft that fly without fuel or electricity?
I was browsing through Wikipedia when I saw this:

An electric aircraft is an aircraft powered by electric motors. Electricity may be supplied by a variety of methods including batteries, ground power cables, solar cells, ultracapacitors, fuel cells and power beaming.

This led me to wonder whether an aircraft could stay airborne/take off without fuel or electricity. (Other than gliders)

Gliders are pretty good at this... Take off is hard though, but hang gliders do it.

I’ve personally flown a man powered airplane.

Wouldn't your kinetic energy be converted into electricity?

https://en.wikipedia.org/wiki/History_of_human-powered_aircraft?wprov=sfti1

Sure, pedal-powered airplanes

Do you count solar-powered aircraft, which do not carry electricity but generate it from sunlight as they go along?

A person powered airplane is powered directly from your legs like a bicycle. Flights of over 100 km have been achieved.

Yes, there are so many sources of energy you can use.
In the simplest form we have Buoyancy, Human power, Fly wheel, Rubber band.
More complicated mechanisms include compressed air, steam, hydrogen peroxide, which you can either use directly as a rocket/jet, or drive a piston engine or turbine to further drive a fan or a prop.....
Or, if you prefer, you can never go wrong with nukes
(Although one could argue nuclear and peroxide(and other mono-propellants) are fuels)
Here I'll just present my favorite out of all the possibilities.

Picture credit: TIHOOD

All are fuel...

@MichaelHall - fuel is stuff you burn to gain energy, so compressed air, flywheels or rubber band motors don't count.

I think the key point is that all heavier-than-air craft need an energy source to overcome drag. A helium balloon can stay aloft for as long as it can contain the gas, with no energy input.

Steam needs fuel or electricity to boil it.

Human powered airplanes exist. They are powered directly from pedaling and don't store energy in any way. My personal experience goes back to my sophomore year at MIT when I helped out on the Chrysalis project in 1979. Chrysalis was a human powered biplane with a wingspan about the size of a DC-9. It was limited by the size of the hanger at Hanscom field outside of Boston. We flew early in the morning when the wind was light enough. I personally flew Chrysalis several times about a mile down the main runway. I also hand towed the plane including pilot when drag measurements were being made.
The principles on that team eventually developed Daedalus which flew from Crete to Santorini. A distance of over 115 km. There are a few YouTube videos of the flight. A detailed write up is available here.

Last I checked, humans (including myself) run on fuel we call "food".  Carbohydrates.  Fats. Proteins.  Our bodies oxidize them for energy we then use to move things like, say, the pedal crank that drives the propeller of our soap bubble aircraft.

@ZeissIkon Of course we don't want to violate the laws of thermodynamics. Even hang gliders require energy from updrafts to stay aloft. I believe my answer is in the spirit of the question since the plane itself stores no energy. It is able to take flight without external sources of power and can maintain level flight for extended periods unaided.

Not even counting the relatively recent electric aircraft and compressed air powered model airplanes, sailplanes depend only on gravity and air currents for their energy (and can be launched by rolling down a slope into the wind, on the right terrain and in the right conditions).
The only other class of aircraft I'm aware of that don't require fuel is gas-type balloons -- not hot air, as those require some kind of fuel (usually propane, these days) to heat the air, but a balloon lifted by hydrogen, helium, or coal gas/methane can float until too much of the gas leaks from the envelope and uses effectively no energy while it does (you could argue that production of the lifting gas uses fuel, but that depends on the gas used).


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Runway Number Landing and Departure Left Traffic Question
If I am "departing runway 36", what does that mean? I understand that runway 36 is at the north end of the runway (360 magnetic); So my question is does the aircraft start at the north end 36 and take off on the south end 18? Or am I starting at the 180 position and taking off at the 360 position/runway 36?
And when landing is it the same or opposite? "Final for runway 36", does that mean the plane is touching down on the 360 north end of the runway heading to stop on the 180/runway 18 side?

RWY 36 means that you are approximately lined up for it, takeoff or landing, if your magnetic heading is 360.
You therefore line up on the south end and depart to the north. You arrive from the south, touch down on the south end TDZ (touchdown zone) and keep pointing north while slowing down.

So either way (takeoff or landing) the pilot destination is in the direction of the runway number? That is how I'm understanding your explanation.

“Destination” could be anywhere. The active runway is chosen based on wind at the surface (take off / land into the wind).  But the aircraft heading is in the direction of the runway number (times 10)

Got it now. I should have said "aircraft heading" instead of destination. Thanks!

There is a misunderstanding here. It is incorrect to say

runway 36 is north end of the runway

Runway 36 is the entire runway, with traffic moving to the north (i.e. facing about 360 degrees, magnetic).  Runway 18 is the same north/south strip of pavement, with traffic moving to the south (i.e. facing about 180 degrees).
If you're lined up ON runway 36, you're at the south end of it, facing north.  If you're on final for 36, you're south of the runway, pointing at it -- again, facing north.
If you are taxiing on the airport surface and need to cross that runway somewhere in the middle, it is correct to be cleared to "cross runway 36..." or to "cross runway 18..." or even to "cross runway 18/36...", typically followed by the taxiway you're to use: "... on taxiway Alpha."  If there is no direction associated with the use, people typically refer to "Runway 18/36" in order to be clear, although sometimes you'll hear only one designation used.  Either way works in that case.
The "Approach End of runway 36" is the end of the runway that you first cross on approach, so the south end.  The "Departure End of runway 36" is the end that you cross after having departed on that runway -- so the north end.  And, the "departure end of runway 36" is the same end of the same strip of pavement as the "approach end of runway 18".  Which description is used depends on context -- i.e. if runway 18 is active (i.e. aircraft are arriving from the north & departing to the south), then controllers are more likely to talk about the approach or departure end of runway 18, than to refer to things in terms of runway 36.


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Is a "stalled" aircraft free-falling?
If I was in an elevator in a sky-scraper and the cable broke, I would free fall and feel weightless until hitting the ground. When I cause a stall on an airplane (power-ff) and the wings stop producing lift, why doesn't the same effect occur?

No if the elevator cable breaks the cabin brakes will engage to stop it and keep the occupants safe.

With some stalls, you might feel weightlessness. But as an important safety point; reduced "g" is not a reliable stall symptom and should not be considered as one. It may not occur at all in shallow stalls, and may occur in lowering-attitude situations that aren't stalls. The "low, slow, ready to spin" situation will usually be 1g.

Note that some aircraft can "fly" in stall mode. The maneuver is known by various names such as "high alpha" and "cobra". Although this is usually done via thrust vectoring engines radio-controlled model aircraft without thrust vectoring have been known to fly in the stall regime via aerodynamic forces (usually aided by prop wash)

The free falling elevator is an idealization in physics, not engineering reality.  It would have to have no air resistance, no resistance from the shaft, no resistance from safety equipment.

@ratchetfreak, Elevators in thought experiments do not have cabin brakes. Providing them with cabin brakes might save the lives of imaginary victims, but it would virtually always defeat the purpose of the thought experiment.

I for some reason read the comments and some of the answers to this question before reading the body of the question itself, and I was quite confused by the references to brakes on elevators!

If the cables break on an elevator (and the safety brakes fail), you won't be in true freefall. You'll still have friction from wind resistance, from the guide rollers on the rails, etc. The same is true in an airplane. Even if you're falling straight down, you'll still have wind resistance.
In addition, lift doesn't just drop straight to zero when the wing stalls (no matter what it might feel like to the pilot). Here's the lift-to-angle diagram for a typical wing:

(wikimedia.org)
This wing stalls at about 16° AoA. But notice that the coefficient of lift doesn't simply drop to zero, it just starts descending at that point. So even in a stall, the wings are still generating some lift, just not enough to overcome the weight of the plane.

Also, at some point beyond the stall angle, the lift coefficient starts increasing again, to a peak at 45°, where the lift coefficient is even higher than at the stall angle (but the vastly-increased drag coefficient prevents most aircraft from maintaining steady-state flight at this high an attack angle).

Is that curve for some GA aircraft? Aren't the wings of most GA aircraft intentionally designed so that the stall starts at the wing root, and progresses out toward the wing tips as the AoA increases? In other words, when you say, "even in a stall the wings are still generating some lift," wouldn't it be more accurate to say, Even when the wing root is stalled, the wing tips may still be generating some lift?

@Solomon Even when flow is separated, there is still lift produced by the separated portion of the wing.

@SolomonSlow Yes, a lot of aircraft (not just GA) are designed like that. The wing will have a different AoA, or different camber, or something to delay stall. But that's only to try and maintain smooth airflow over the ailerons for as long as possible. The stalled section(s) of the wing will still produce some lift. Thus, each section of the wing will have a similar lift-to-AoA diagram (just with the stall point in different places), and the overall wing will also have a similar lift-to-AoA diagram for its overall (average?) AoA.

The stall feels like a sudden free fall because the back side of the lift curve is an unstable zone. The slight decrease in lift after the peak causes an increase in vertical decent speed which in turn increases the AoA which further decreases lift... and this loop very quickly compounds to give the sensation that lift suddenly disappeared.

Is a “stalled” aircraft free-falling?

No!

If I was in an elevator in a sky-scraper, and the cable broke, I would free fall and feel weightless (until hitting the ground of course). When I stall an airplane(power-off) and the wings stop producing lift, why doesn't the same effect occur?

Because in a stall, the aerodynamic force component acting against the direction of the weight vector is not actually zero.  In fact, after a very short time it becomes equal to the weight vector, thus yielding a steady-state situation in the vertical plane.  Lift and drag, as conventionally defined, both contribute to this aerodynamic force component; lift is by no means zero even in stalled flight.  In a stall, you are definitely not free-falling.  You are just flying along a very poor glide ratio or descent ratio.  After the first few seconds, you are no longer accelerating.  An aerodynamic force exists that not only limits the rate of downward acceleration, but also yields a specific downward terminal velocity, as well as as a specific forward speed.

Basically, you can look at a stalled aircraft as a very poor parachute.

@MikeBrass As a hang-glider pilot, that's exactly how my instructor described it. In hang-gliding, when you land you rotate the wing to give a rapid stall and turn it into an airbrake. If you've got too much speed though, you go up a bit. You then have to hold your nerve and ride it down like a "very poor parachute", because otherwise it tries to recover from the stall and you'll plant into the ground like a lawn dart.

"In fact, after a very short time it becomes equal to the weight vector, thus yielding a steady-state situation in the vertical plane." -- Is that not also true for our poor, doomed elevator?

@WayneConrad Indeed, that would be true for any falling object that's not accelerating - it's reached terminal velocity. In reality, falling objects are only truly "weightless" at the very start of their descent when drag is near-zero, so a person in a falling elevator is not really weightless, just like a person in a stalled plane.

@WayneConrad I am not sure if an elevator "flight level" is high enough to get even close to a terminal velocity before reaching the ground.

@Suma I'm not sure either.  The only thing I know for sure about the elevator is that it is going to go off of the controller's scope very soon.

A stall is not a free-fall.  It is a loss of laminar airflow over the wing, resulting in a loss of lift.  The response to a stall is to stop the (usual) roll induced by one wing stalling before the other.  Then drop the nose - most aircraft will do this by design - until you achieve a flyable speed with proper airflow over the wing.  The problem here is that you may not have enough altitude to reach that speed >> crash.  I once stalled and dropped from over 25000 (not looking at altimeter) to under 12000 before I had enough airspeed to pull up.  With the resulting pucker factor I bottomed out at around 7000 ft.

Speaking as a commercial pilot, pilot instructor and skydiver I think I can answer this.
An aircraft has a centre of pressure, which is the lift vector that comes out of the wing and opposes the weight.  As you increase the angle of attack of the wing, up to around 16 degrees angle of attack, the centre of pressure (lift) moves slowly forward.  When you stall, the boundary layer which is the area of low pressure air sucking the wing upwards, rips off and the centre of pressure moves rearwards, behind the centre of gravity.  This drops the nose of the aircraft.  The drop of the nose reduces the angle of attack and the wings start to fly again.
Even if you hold the aircraft in a stall at the buffet, the wing will still drop and attempt to fly again repeatedly. So, you're never in freefall, which would assume terminal velocity, you're just pitching up and down as you move forwards in the stall.
Freefall, as a skydiver, implies no forward movement and no lift, even though many skydiving diciplines do involve both such as tracking, wingsuiting and even formation, where you de-arch to slow yourself down and rise relative to others.


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How did SR-71 spy, flying at 80,000 ft and 3500 km/h?
The SR-71 Blackbird is a famous supersonic reconnaissance/spy aircraft, undoubtedly one of the most amazing flying machines ever. Now, with the capabilities it had:

Maximum speed: Mach 3.3 (2,200+ mph, 3,540+ km/h, 1,910+ knots) at
  80,000 ft (24,000 m)

How was it used for spying? It must have been difficult to focus on any object on the ground, from such a great height and then many problems are encountered with high speed photography. How were these and many other problems overcome?

Cameras are faster than the speed of sound :)

Actually that depends @egid. https://en.wikipedia.org/wiki/Shutter_(photography)

I spy with my hugely complex big expensive and top secret eye ...

Consider that satellites "fly" higher and faster and provide quite good images of the earth.

The SR-71 Blackbird was equipped with specialized cameras. It would overfly the area of interest and take high-resolution pictures of the ground.
Of particular interest is the Technical Objective Camera (TEOC). It could shoot pictures with a 6'' resolution from the operational altitude of the SR-71. This task was not simple as the aircraft would have moved several hundred feet forwards during the exposure time of the picture which was (depending on the settings) around one or two tenths of a second. Without some kind of correction, this would have resulted in a picture that was blurry in the direction of motion of the aircraft.
To solve this, the velocity over height ratio number was fed to the camera, either manually as computed by the pilot or automatically as computed by the sensors and computer of the SR-71 (and it turns out that the machine did a better job at this than the pilot) and while the picture was taken, the high-precision mirror that directed the camera FOV downwards would rotate in the opposite direction towards which the airplane was moving, thus cancelling it out.

Great answer. Do you happen to have any information on how large the entire area covered by the picture was, and how the pictures were taken (i.e. plan one large picture of a specific area, or fly over an area and automatically shoot smaller pictures at a constant rate)?

This picture shows an approximate size of the ground aerea that can be photographed using the various cameras on board the SR-71. The yellow areas on the middle are what the TEOC can cover. As you can see, if the camera is targeted towards the ground on a right angle they are 2.4 nautical mile wide squares.

Do you have a source for this? It sounds like a very interesting mechanism!

This badly written website as well as those two books.

This is the section of the original SR-71 operation manual that describes in detail how the camera works. The plane was equipped with an Optical Bar Camera

"The Optical Bar Camera (OBC) is a high resolution panoramic camera
  with a "folded" ----------- lens system. It provides continuous
  ------- or --------- coverage along the flight track through an angle of 70 degrees on each side of the aircraft.

Note: the ----- are blacked out sections in the manual.
The manual goes on to talk about the operations of the camera and also notes that it takes 5 inch film with is way bigger (and subsequently higher "resolution") than the 35mm you would use in a home camera.
Here are the actual cameras. The left is the Technical Objective Camera and the right is the Optical Bar Camera.

source
The resolution of the TEOC was pretty great

Programmable system with a 48 inch focal length. The TEOC resolution
  was 110 lines per millimeter, which equates to about 6" ground
  resolution from an operational altitude. The TEOC's were mounted both
  sides of Chine controlled by a computer

The OBC seems like it may have been more size than resolution

The OBC could photograph 100,000 square miles of the Earth's surface
  per hour. Film image 72 miles wide, & film length 10,500ft.

And of course you cant have a fancy plane with out lots of buttons and knobs. The control systems for the cameras looked like this

For what its worth it seems that both of these cameras were really high tech panning control systems for cameras. They are very similar to Equatorial Mount cameras which are used to photograph stars (since the earth is moving), it's also called a barn door tracker.
(image source, all images)

Thanks for the photos. I didn't know the word "chine", so here it is: https://en.wikipedia.org/wiki/Chine_(aeronautics)

@ChrisW You can edit those links in directly.

@Lilienthal Thanks but no, the word "Chine" is in quoted text and the link isn't really part of the quote.

Dave,  can you provide proper image attribution above, please? (source)

@ChrisW Given that the the source predates the internet I'm sure it won't be grounds for confusion.

It seems the image source link was edited out ill put it back in.

Film image 72 miles wide, & film length 10,500ft.  What does that mean, surely the actual film wasn't that big?!

@Michael I think that is a typo or autocorrect. 72 mm is 2.8 inches which is about how wide the film reels look.

@Michael unless it means the image was a 72 mile wide area, Ill look into it and see where i got that from

Left out of your answer is that the first image was taken on approach by an SR-71 when it was still 2 miles away....

Yes, the OBC (by Itek) did have 10,500 feet of 5" wide very fine grain Kodak film. As I recall, in non-overlapping mode it could cover over 2900 miles of terrain, and in stereo (overlapping mode) 1300 or so miles. So, each negative was 4.5" x 72". It also had v/r sensors and servos to tilt the view fore & aft during each exposure for image motion compensation as in the Hycon TEOC. The OBC principle was utilized in other reconnaissance aircraft at lower altitudes as well.